<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.6.10/dist/vue.js"></script>
</head>
<body>
    <div id="app">
        <!-- 书写v-pre的模板,直接被当作静态节点,不再被vue编译 -->
        <h2 v-pre>用户名:{{username}}</h2>
        <h2>用户名:{{username}}</h2>
        <p>修改用户名</p>
        <input type="text" v-model="username" />
    </div>
    <script>
        Vue.config.productionTip=false

        const vm=new Vue({
            el:"#app",
            data(){
                return{
                    username:"laoli"
                }
            }
        })
    </script>
</body>
</html>